Harness safety device for aircraft seats



Nov. 30, 1965 J. MARTIN HARNESS SAFETY DEVICE FOR AIRCRAFT SEATS 5Sheets-Sheet 1 Filed Feb. 15, 1964 In ven [or 6 Mas/74 m Nov. 30, 1965.J. MARTIN HARNESS SAFETY DEVICE FOR AIRCRAFT SEATS 5 Sheets-Sheet 2Filed Feb. 13, 1964 Inventor N v. 30, 1965 J. MARTIN 3,220,668

HARNESS SAFETY DEVICE FOR AIRCRAFT SEATS Filed Feb. 13, 1964 5Sheets-Sheet 3 Inventor I Nov. 30, 1965 J, MARTIN Q 3,220,668

HARNESS SAFETY DEVICE FOR AIRCRAFT SEATS Filed Feb. 13, 1964 5Sheets-Sheet 4 I nuenlor Nov. 30, 1965 J. MARTIN HARNESS SAFETY DEVICEFOR AIRCRAFT SEATS 5 Sheets-Sheet 5 Filed Feb. 13, 1964 Inventor(712.45% Ar United States Patent 3,220,668 HARNESS SAFETY DEVICE FORAIRCRAFT SEAT This invention concerns aircraft seats and is especiallyconcerned with harness arrangements for securing an occupant in such aseat; the invention is especially applicable to the harness arrangementsof aircraft ejection seats.

It is known to provide an aircraft seat with a harness arrangementhaving forward reach facility with a control mechanism which, whenoperated, frees the harness shoulder straps in a manner permitting theseat occupant to lean forwardly. Such an arrangement is, for instance,disclosed in the specification of Patent No. 3,036,796. It is also knownto incorporate an inertia lock in such an arrangement, such inertia lockautomatically responding to specified acceleration conditions tooverride the forward reach control mechanism, if in operated condition,thereby so to lock the shoulder straps as to restrain movement of theseat occupant forwardly of the seat.

Usually, harness arrangements having a forward reach facility (with orwithout inertia lock) comprise shoulder straps that are associated withat least one spring-loaded reel that maintains light tension in suchstraps when the forward reach facility is in use.

With such arrangement, when the forward reach facility is inoperative,the harness shoulder straps may be tightened, eg by means of adjustmentbuckles, to secure the seat occupant firmly and comfortably in the seat.However, following operation of the forward reach control mechanism, thetension in the shoulder straps is determined by the spring loading ofthe reel or reels associated with the straps and, when the forward reachfacility is subsequently rendered inoperative, the shoulder harnessstraps will usually be slacker than is desirable, since the tensiontherein, prior to rendering the forward reach facility inoperative, isgenerally considerably less than that required to retain the seatoccupant firmly and comfortably in the seat. Accordingly, the seatoccupant, if he wishes to restore to the harness shoulder straps thegreater tension existing prior to operation of the forward reach controlmechanism, must resort to deliberate re-adjustrnent of the straptension, e.-g. by means of the aforesaid adjustment buckle-s.

This is undesirable for two reasons: first, the re-tightening of theharness shoulder straps by means of adjustment buckles involvesdistraction of the seat occupants attention from other duties; secondly,if the forward reach control mechanism is operated several times in thecourse of a flight and the seat occupant re-adjusts the harness shoulderstrap tension each time the forward reach facility is renderedinoperative, the repeated adjustment of the harness shoulder straps willprogressively take up the amount of forward movement permitted to theseat occupant by the forward reach facility when in use and therebyrender the latter of decreasing utility. In addition, the amount ofadjustment obtained by adjustment buckles is usually limited, andcontinual re-adjustment may eventually take up all the adjustmentavailable.

These disadvantages of the known arrangements cannot satisfactorily beovercome by providing an increased spring-loading on the reel or reelsassociated with the harness shoulder straps, since any such increase inspringloading compromises the freedom of the seat occupant to moveforwardly in the seat when the forward reach facility is in use.

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Accordingly, the principal object of the present invention is to providea seat harness arrangement including a forward reach facility and meansfor readily restoring harness shoulder strap tension to a desired valueafter use of the forward reach facility without recourse to devices suchas adjustment buckles.

Thus, the present invention provides a seat harness arrangementincluding harness shoulder straps associated with at least onespring-loaded reel, such reel coacting with a manually operable ratchetmechanism for rotating the reel in the sense to wind in said straps forin creasing the tension therein.

Conveniently, such ratchet mechanism comprises a ratchet wheel rigidwith said reel and a pawl reciprocable by means of a manually operabledevice so as to engage and incrementally rotate said ratch wheel in thesense to wind in the harness shoulder straps, rotation of the ratchetwheel in the opposite sense being restrained by a control pawl riding onsaid ratchet wheel. Said control pawl may conveniently constitute partof the control mechanism for the forward reach facility, said controlpawl being coupled to a forward reach control device whereby such pawlmay be withdrawn, when desired, from engagement with the ratchet wheelso as to free the reel for rotation in the sense to pay out the harnessshoulder straps.

Said control pawl may also constitute part of an inertia lock, thecontrol pawl cooperating with an acceleration-sensitive spring togglemechanism that responds to predetermined inertia loads to cause thecontrol pawl to engage the ratchet wheel independently of the conditionof the forward reach control device.

Whilst the invention is generally applicable to aircraft seat harnessarrangements, it is especially applicable to harness arrangementsincorporating a harness shoulder strap retraction mechanism such asdisclosed in my simultaneously filed copending application Ser. No.344,613. A typical embodiment of the present invention as applied to aseat harness arrangement having retraction mechanism as disclosed insuch copending application is illustrated, by way of example, in theaccompanying drawings in which:

FIGURE 1 is a front View of a combined retraction mechanism, inertialock and harness tensioning device;

FIGURE 2 is a horizontal medial sectional view on the line II-II ofFIGURE 1;

FIGURE 3 is a partly sectioned end view of the mechanism of FIGURE 1;

FIGURE 4 is a sectional View of the mechanism taken on the line 1V-IV ofFIGURE 1;

FIGURE 5 is a fragmentary sectional view taken on the line VV of FIGURE2; and

FIGURE 6 is a sectional view taken on the line VIVI of FIGURE 2.

The retraction mechanism illustrated in the accompanying drawings isfully described in the specification of my said copending application.As disclosed in such specification, the retraction mechanism comprises ahollow shaft I mounted for rotation on the supporting frame 25 of anaircraft ejection seat, only partly shown in the drawing, the shaft 1being formed integrally with a pair of reels 2 each having woundtherearound a strap 3 passing forwardly from the reel 2 to constitute aharness shoulder strap for the seat occupant. One end of the hollowshaft 1 extends into a housing 4 and has a pinion 5 fixed thereto forco-operation with a rack 6. The rack is arranged for reciprocation in acylinder 21 carried by the housing 4, the rack having a piston 22 on oneend thereof so that admission of pressure fluid through the bore 23 tothe cylinder 21 drives the rack 6 and rotates the pinion 5 by means ofwhich the shaft 3 1 is rotated in the sense to wind in the shoulderstraps 3 on to their respective reels 2.

The hollow shaft 1 is supported for rotation with respect to a centralspindle 7 within the bore of the shaft 1, the spindle 7 having a torsionspring 8 arranged therearound and anchored at one end at 9 to thespindle and at its other end at 10 to the shaft, thereby to tend torotate the hollow shaft 1 in the sense required to wind in the straps onto the reels 2 of the shaft 1. One end of the spindle 7 is anchored onthe frame against rotation.

The mechanism incorporates a forward reach facility provided by tworatchet wheels 11 on the hollow shaft 1 and a control pawl 12 associatedwith each wheel which may be held out of engagement with the ratchetwheel 11 by operation of a suitable forward reach control deviceassociated with such pawl 12 to enable the straps to be paid out inresponse to forward movement of the occupant in the seat, but which maybe engaged with the ratchet wheel 11 to prevent paying out of the strapswithout, however, hindering reeling-in of the straps under the influenceof the torsion spring 8 or of the aforesaid rack 6. The pawls 12 aremoved by rotating a shaft .13, such shaft carrying a radius arm (notshown) connected to a cable leading to an operating lever positioned onsaid seat so that the seat occupant may, by manual operation of saidlever, engage or disengage said pawl 12 from the wheel 11.

In this embodiment the control pawls 12 are associated with an inertialock comprising an acceleration-sensitive over-centre spring togglearrangement essentially consisting of two telescopically engaged hollowbars 14, 14a, an arm 1412, a helical compression spring 140 andassociated pivots, as shown in FIG. 4. The arm 14b is fixed to the shaft13 and hingedly attached to the end of the bar 14a projecting from thebar 14. The end of the latter remote from the arm 14b is pivotallyattached to the supporting frame 25. The spring 140 is received in thecommunicating bores of the bars 14, 14a to bias the bar 14a outward ofthe bar 14. Abutments on the bars 14, 1411 (not shown in detail) preventthe spring 140 from pivoting the arm 14b in a clockwise direction beyondthe illustrated position. The spring 140 and a pendulous weight 15 acton the shaft 13 to cause, independently of the forward reach controldevice, engagement of the control pawl 12 with the ratchet wheel 11 inresponse to predetermined inertia loads, e.g. loads due to accelerationof the seat during ejection thereof, when the weight pivots the shaft 13counterclockwise, as viewed in FIG. 4, beyond the deadcenter position ofthe toggle arrangement.

In accordance with the present invention, a piston member 16 is arrangedfor reciprocation in a tubular guide 17 adjacent to the periphery of theratchet wheel 11, this piston member 16 having a slot 17 housing a pawl18 engaged by a spring-loaded plunger 19 which biasses the pawl towardsengagement with the teeth of the ratchet wheel 11.

A spring 20, acting between said piston member 16 and the guide 17 forsame, urges the piston member 16 in a direction corresponding torotation of the ratchet wheel in the sense for paying out the harnessshoulder straps 3 from their respective reels 2, and towards theillustrated position in which the pawl 18 is retracted clear of theratchet wheel teeth by engagement with the wall of a guide channel 17a,coaxial with the guide 17, which is a part of the support structure ofthe seat.

The piston member 16 is coupled to a non-illustrated flexible cable inturn connected to a control lever, whereby manual operation of suchlever, by the seat occupant,

moves the piston member 16 in the direction opposed to the thrust ofsaid spring 20, whereby the pawl 18 carried by the piston member 16 willengage the teeth of the ratchet wheel and rotate the same in the sensecorresponding with winding-in of the harness shoulder straps 3.

From the foregoing description it will be understood that, when thecontrol pawl 12 is engaged with the ratchet wheel 11 to prevent rotationof the latter in the sense for paying out the harness shoulder straps,reciprocation of the control lever will cause incremental rotation ofthe ratchet Wheel 11 in the sense to wind-in the shoulder straps 3 on tothe reels 2 for same, whereby the shoulder straps may be tightened to adesired degree.

I claim:

1. In a vehicle seat, in combination:

-(a) a support;

(b) .a harness strap;

(c) a reel rotatably mounted on said support, a portion of said strapbeing attached to said reel;

(d) spring means biasing said reel in the sense to wind said strapthereon; and

(e) restraining means cooperable with said reel to restrain rotationthereof in the sense to pay out Said strap, and manually operableactuating means for indexing said reel incrementally in a sense to windsaid strap thereon, said restraining and actuating means including (1) aratched wheel secured to said reel,

(2) a piston member,

(3) guide means guiding said piston member for movement thereoftangentially to said wheel between a first position and a secondposition,

(4) a pawl mounted on said piston member for movement between anoperative and a retracted position, said pawl being spaced from saidratchet wheel when in said retracted position,

(5) first yieldably resilient means biasing said pawl toward theoperative position thereof for engagement with said ratchet wheel whensaid piston member approaches said first position from said secondposition thereof,

(6) engagement means on said guide means for holding said pawl in saidretracted position thereof when said piston member is near said secondposition thereof, and

-(7) second yieldably resilient means biasing said piston member towardsaid second position.

2. In a vehicle seat as set forth in claim 1, said restraining meansincluding a cotnrol pawl engageable with said ratchet wheel. 1

3. In a vehicle seat as set forth in claim 2, means responsive to apredetermined acceleration of said support to move said control pawlinto engagement with the ratchet Wheel.

References Cited by the Examiner UNITED STATES PATENTS 730,868 6/1903Brown 242107.4 2,403,553 7/1946 Rosinski 242 X 2,471,194 5/1949 Capps74-128 2,630,181 3/1953 Solum 74-160 X 2,838,190 6/1958 Stevens 242107.4X 3,018,065 1/11962 Cushman et a1 242-1074 FOREIGN PATENTS 195,8914/1923 Great Britain.

MERVIN STEIN, Primary Examiner.

1. IN A VEHICLE SEAT, IN COMBINATION: (A) A SUPPORT; (B) A HARNESSSTRAP; (C) A REEL ROTATABLY MOUNTED ON SAID SUPPORT, A PORTION OF SAIDSTRAP BEING ATTACHED TO SAID REEL; (D) SPRING MEANS BIASING SAID REEL INTHE SENSE TO WIND SAID STRAP THEREON; AND (E) RESTRAINING MEANSCOOPERABLE WITH SAID REEL TO RESTRAIN ROTATION THEREOF IN THE SENSE TOPAY OUT SAID STRAP, AND MANUALLY OPERABLE ACTUATING MEANS FOR INDEXINGSAID REEL INCREMENTALLY IN A SENSE TO WIND SAID STRAP THEREON, SAIDRESTRAINING AND ACTUATING MEANS INCLUDING (1) A RATCHED WELL SECURED TOSAID REEL, (2) A PISTON MEMBER, (3) GUIDE MEANS GUDING SAID PISTONMEMBER FOR MOVEMENT THEREOF TANGENTIALLY TOI SAID WHEEL BETWEEN A FIRSTPOSITION AND A SECOND POSITION, (4) A PAWL MOUNTED ON SAID PISTON MEMBERFOR MOVEMENT BETWEEN AN OPERATIVE AND A RETRACTED POSITION, AND PAWLBEING SPACED FROM SAID RATCHET WHEEL WHEN IN SAID RETRACTED POSITION,(5) FIRST YIELDABLY RESILIENT MEANS BIASING AND PAWL TOWARD THEOPERATIVE POSITION THEREOF FOR ENGAGEMENT WITH SAID RATCHET WHEEL WHENSAID PISTON MEMBER APPROACHES SAID FIRST POSITION FROM SAID SECONDPOSITION THEREOF, (6) ENGAGEMENT MEANS ON SAID GUIDE MEANS FOR HOLDINGSAID PAWL IN SAID RETRACTED POSITION THEREOF WHEN SAID PISTON MEMBER ISNEAR SAID SECOND POSITION THEREOF, AND (7) SECOND YIELDABLY RESILIENTMEANS BIASING SAID PISTON MEMBER TOWARD SAID SECOND POSITION.